A driver of a vehicle drives while looking forward through a front windshield, and visually checking instruments on an instrument panel. That is, the gaze shifts forward and to the instruments below. If the instruments can be seen while looking forward, there will be no shift of gaze, so improved drivability can be expected. From this knowledge, head-up display devices have been developed and are being put into practical use (see Patent Literature 1 (FIG. 1 and FIG. 2), for example).
FIG. 1 of Patent Literature 1 is reproduced. However, the reference numerals have been renumbered. A head-up display device 100 according to the related art shown in FIG. 9 is mounted on an upper surface of an instrument panel 102 of a vehicle that is positioned behind a front windshield 101. Light emitted from a display 104 stored in a case 103 is first reflected by three reflectors 105, and then emitted upward from the case 103 and illuminated toward a translucent reflector 107.
The translucent reflector 107 has two functions, i.e., a reflective function and a translucent function, and is therefore typically referred to as a combiner (multifunction device). Hereinafter, the translucent reflector 107 will be referred to as combiner 107.
The combiner 107 is stored in the case 103 so as to be out of the way, when not in use. More specifically, the combiner 107 is placed in a horizontal state from an upright state by a combiner tilting mechanism 108, and then a cover 111 that is supported by guide rails 109, 109 that extend in the front-back direction of the drawing is moved in the front-back direction of the drawing (FIG. 2 of Patent Literature 1) by a cover moving mechanism 112. As a result, the combiner 107 that is in the stored state is covered by the cover 111.
Because the cover 111 moves in the vehicle width direction (the front-back direction in FIG. 9), a space in the vehicle width direction that is more than two times the width of the cover 111 is occupied. As a result, the degree of freedom of arrangement of equipment arranged inside the instrument panel 101 is reduced.
As a countermeasure, it is conceivable to move the cover 111 in the longitudinal direction of the vehicle. If an attempt is made to move the cover 111 in the longitudinal direction of the vehicle, the dimension of the head-up display device 100 in the longitudinal direction of the vehicle will inevitably become long. As a result, the vehicle cabin volume will be affected.
Also, in recent years, the number of vehicles in which curved glass is employed for the front windshield 101 to enhance the design has increased. As shown by the imaginary line in FIG. 9, if a lower part of the front windshield 101 is made to curve downward, the curved glass will interfere with a front part of the head-up display device 100. However, from the viewpoint of design, a structure that is better suited for curved glass is needed.
That is, in a head-up display device that is provided with the combiner 107 and the cover 111, and in which the cover 111 moves in the longitudinal direction of the vehicle, a head-up display device that is compatible with a curved front windshield is needed.